P.S.Questions 65 350hp w A/C

[Joe L.]

Re: P.S.Questions 65 350hp w A/C

Hi Joe:

Thanks for digging out your 3868892. I just want to clarify what you mean by the 0.44" difference.

I would expect the 3868892 to place the belt groove of the pulley farther forward (farther from the pump resevoir) than the 377509. The reason is that if the 3868892 is intended to line up with the 3827843 add-on pulley that seats properly in the 3858533 crank pulley, the centerline of the belt groove would have to move forward by the difference in thickness between the standard-groove 3850838 dual crank pulley and the 3858533 deep-groove dual crank pulley. I believe that difference is approximately .330 inches.

Joe-----

I had the 3770509 and 3868892 reversed in the 3rd paragraph of my first post in this series. I have corrected that. The 3868892 would mount the furthest from the pump. The 3770509 would mount the next closest and the 3834720 would be the closest of all. The dimensions I provided are the closest I can determine without actually mounting the pullies on a pump and then measuring. They should be pretty close, though.

[Mark G.]

Re: P.S.Questions 65 350hp w A/C

Joe -

Outstanding effort, I see you also have the 3844099 hubs securely braised in the proper postions. So the P/S is set for the '65 L79, I need more information on the pesky 3848904 W/P pulley. It's identical with the 3770245 spacing, except the cone angle and the diameter.

When did the '904 appear and did it coincide with a water pump change?
Could this '65 L79 pulley configuration creep into '66-'67 A/C only applications?
Does the 3883235 A.I.R. pulley fit on the front of the '904 W/P pulley?
Please email me.

Mark

[Joe L.]

Re: P.S.Questions 65 350hp w A/C

Joe -

Outstanding effort, I see you also have the 3844099 hubs securely braised in the proper postions. So the P/S is set for the '65 L79, I need more information on the pesky 3848904 W/P pulley. It's identical with the 3770245 spacing, except the cone angle and the diameter.

When did the '904 appear and did it coincide with a water pump change?
Could this '65 L79 pulley configuration creep into '66-'67 A/C only applications?
Does the 3883235 A.I.R. pulley fit on the front of the '904 W/P pulley?
Please email me.

Mark

Mark------


The GM #3848904 first appeared in the fall of 1964 for use on "64-65 with SHP 327 and A/C" I don't think there were any 1964 such applications but I suppose it's possible towards the end of the model year.

The 3848904 continued to be used for quite a few years. It is supposed to have been used for 1966-68 L-79 with A/C except N-40 and late 1968 L-79 without A/C. It was also used for some early 1968 427's as well as 1968-69 L-88. Finally, it was used for 1969-70 L-46 and LT-1 except those also equipped with A/C.

The 3848904 was discontinued in September, 1972 and replaced by the SERVICE-only GM #3995641 which remains available from GM to this very day.

I think that the GM #3883235 will work in conjunction with a GM #3848904 but I cannot confirm that. I know it will work in conjunction with the 3995641 and if it works with this pulley it should work for the 3848904 (otherwise, the 3995641 would not have been an acceptable SERVICE replacement for the 3848904).

Also, there was a change in waterpump part numbers between the 63 and 64 model year. The pump specified for the 1963 (and earlier) model years was GM #3787566 and for the 1964 model year it became 3848072 (which also later SERVICED all earlier applications). Installation instructions for both pumps specified that for 62-65 models the hub had to be driven 1/8" further onto the shaft. However, not too much can be drawn from these pump part numbers as I'm pretty sure these are SERVICE part numbers and not necessarily the same as those used in PRODUCTION. In PRODUCTION I'm sure there were pumps with the different hub spacings (and different part numbers) available.

[Joe L.]

Re: P.S.Questions 65 350hp w A/C

All------


Look what I came up with----an NOS GM #3827843 add-on crank pulley. So, they definitely exist. [not for sale]

[Joe R.]

Re: P.S.Questions 65 350hp w A/C

All------


Look what I came up with----an NOS GM #3827843 add-on crank pulley. So, they definitely exist. [not for sale]

Hi Joe:

Thanks for digging that out. I have just returned from Carlisle, and every time I saw the proverbial "box of pulleys" I dug through them to see if I could find either the 3827843 add-on pulley or the 3868892 pump pulley from 1965. No luck on either one.

I did see a LOT of the later 346290 add-on pulleys, which I think may be functionally identical to the 3827843. If you have an available 346290 to compare to your 3827843, I would be interested to hear your assessment of how they compare.

I did came home with an as-yet unidentified pump pulley that is similar to the 509 but with a distinctly farther-forward groove placement. It's a greasy mess, so when I clean it up I may find a part number. The seller said he thought it was from a big block, which sounds likely.

[Joe R.]

Re: P.S.Questions 65 350hp w A/C

Hi Joe:

I did came home with an as-yet unidentified pump pulley that is similar to the 509 but with a distinctly farther-forward groove placement. It's a greasy mess, so when I clean it up I may find a part number. The seller said he thought it was from a big block, which sounds likely.

Hi Joe L:

I cleaned off the "mystery pulley" and found it has part number 9778555. It is a stamped-steel, taper-hole, single deep-groove pulley with a groove centerline that is about 0.6 inches farther forward than the 509. Do you what its original application was?

[Joe L.]

Re: P.S.Questions 65 350hp w A/C

Hi Joe L:

I cleaned off the "mystery pulley" and found it has part number 9778555. It is a stamped-steel, taper-hole, single deep-groove pulley with a groove centerline that is about 0.6 inches farther forward than the 509. Do you what its original application was?

Joe-----


9778555 is a Pontiac part number and was never used for any Chevrolet application I can find. So, the guy was partially correct; it was used for a "big block"-----a PONTIAC big block. I'd say it was some 60's application but I don't know which one. It was discontinued without supercession in July, 1978.